\cache::make() may return a cache_disabled subclass but callers, specifically
user/lib.php:user_create_user(), invoke \cache::purge_current_user() which was
only implemented by the cache_session subclass. Added empty
\cache::purge_current_user() which subclasses can implement, i.e.
cache_session, or not, i.e. cache_disabled.
The current logic in the cache_session::check_tracked_user() is not
right. We must always set the current session id. A typical use case is
when the cache instance is instantiated for a not logged in user. We
can't let the sessionid property null in that case as it forms an
important part of the parsed key.
Similarly, even if we have the same user currently loaded, we must still
set the sessionid to make sure the data will be associated with the
current PHP session. Same user (including visitors or guest users) can
access the site from different browsers and each must end up with its
own key prefix.
It is now safe to cache a reference to a cache and expect consistent results.
Changing identifiers altered cache results where a reference was
held to the cache. Identifiers have been set to be cached with
identifiers included so the caches are separate.
As a consequence of this it was identified that invalidation events
and identifiers don't easily work together as an event can't determine
which identifiers should be used for cache invalidation. So invalidation
events have been made incompatible with identifiers being set. No core
code used this combination as it's not possible to understand any expected
behaviour.
Event invalidation for application and session caches was centralised to the same
location. The only difference was the name of the lastinvalidation variable. This
improves support and consistency of invalidation code.
Static cache has a very flexible storage capability
and does not need all the checks performed on it.
Enabling dereferencing handling and multiple identifiers
removes a lot of unneeded overhead for request caches that
have many get calls.
The changes were modelled on the static acceleration changes
done in MDL-53208.
When a cachable object is store in the static cache from
the backing store, it was incorrect serialised rather than
using the wake function. This has been resolved and tests added.
During the investigation into cacheable_object, it was discovered
that set_identifiers never removes identifiers when you call it,
so set_identifiers(array('a')) and set_identifiers(array('b')) really
resulted in array('a','b') as the identifiers rather than 'b'.
The fix for this issue depends on the set_identifiers fix and
they have been coupled together as a result.
- We only now serialize when required, eg when the store doesn't do it.
- static acceleration now serializes on set to reduce overhead on load.
- null now works in static acceleration as we use an array for storage metadata
- static acceleration delete uses isset rather than an array_search.
- We only now serialize when required, eg when the store doesn't do it.
- static acceleration now serializes on set to reduce overhead on load.
- null now works in static acceleration as we use an array for storage metadata
- static acceleration delete uses isset rather than an array_search.
The cache store mode is now included in the performance stats
printed at the bottom of the page.
It is represented as either [a] [s] or [r] and a title is used
to actually state the mode.
Cache data source aggregate functionality was found to be broken
and unused, because of this the decision was made to remove it
rather than fix it.
As it was broken we did not follow typical deprecation methods and
instead the code was removed outright with only structure
remaining and left deprecated.
This issue makes several fixes for the session loader and the session store.
* maxsize argument now works for session caches.
* fixed performance hole when interation occurs frequently.
* fixed cache purge bug occuring when multiple caches are defined before being used.
* improved lastaccess handling.
Big thanks to Marina who contributed the following commits:
* Always make sure the elements in cache are sorted so we need to remove only elements in the beginning of array
* Remove expired elements from session store to free memory
* Minor bug fixes
This issue makes several fixes for the session loader and the session store.
* maxsize argument now works for session caches.
* fixed performance hole when interation occurs frequently.
* fixed cache purge bug occuring when multiple caches are defined before being used.
* improved lastaccess handling.
This change is a large change to the way sessions are handled
within MUC after it was discovered that session did not function
as expected when any store other than the default session store
was being used.
As part of this change the session loader has been largely
customised in order to consolidate session data for the loader.
The unit tests have also being greatly increased to provide
better coverage for sessions.
